Curtain for electrolytic cells



Oct. 20, 1931. L. E. WARD I CURTAIN FOR ELECTROLYTIC CELLS 2 Sheets-Shet 1 Filed July 29, 1929 .Ill 1.. II=FE INVENTOR BY 111M ATTORNEY L. E. WARD CURTAIN FOR ELECTROLYTIC CELLS Filed y 29, 1 2 Sheets-Sheet 2 I INVENTOR JW filming p ATTOR N EY Oct. 20, 1931.v

Patented Get. 120, 1931 LOUIS E. WARD, F MIDLAND, MICHIGAN, ASSIGNOB. TO THE DOW CHEMICAL COANY CURTAIN FOR ELECTROLYTIC CELLS Application filed July 29,

This invention relates in general to a curtain-like means for separating anodic from cathodic products of electrolysis. It relates specifically to a sectional type of curtain adapted for use in separating metallic magnesium and chlorine gas produced by the electrolysis of a fused saline bath containing magnesium chloride.

Owing to the high temperature to WhlCh such a curtain is exposed, the corrosive action of chlorine and other anodic products and further to the fiuxing or erosive action of the fluid hot metal upon ceramic ware in general, and still further to the necessity that the ourtain have electrical non-conductive property, the choice of material for such a curtain is somewhat narrow and the details of .construction require careful design. Refractory material such as fire-clay or brick shapes is 2 customarily employed and because such material suffers erosion, corrosion, or breakage it is essential that the details of design shall permit the easy substitution of new parts to replace those no longer serviceable. It may be stated, in general, that such pieces of large size are relatively more expensive than those of small size, are, more difficult to pack, ship, unpack, and store without breakage'and are more readily broken when handled in a re- 3 placement operation. Small pieces, on the contrary, are more cheaply made, more easily packed and transported, easily stored in small space, and can be handled with a minimum of breaka e and loss.

I have invented a curtain composed of a plurality of suitably shaped plates of simple design and small size and have invented further means to construct same and means to support said plates in the cell permitting the easy removal and replacement of any single piece even without suspending operation of the cell during such repairs.

To the accomplishment of the foregoing and related ends, the invention, then, consists of the means hereinafter fully described and particularly pointed out in the claims, the annexed drawings and the following description setting forth in detail certain means for carrying out the invention, such disclosed 50 means illustrating, however, a but several of 1929. Serial No. 381,794.

to show my improved curtain and other details. Fig. 4 is a transverse section through the form of curtain shown in Figs. 1, 2, and 3. Fig. 5 is a plan of the same curtain assembly and Fig. 6 a side elevation thereof With a portion of the near side brokenaway to show in cross section a strut hereafter described. Fig. 7 is an end elevation of the said curtain assembly. Fig. 8 is a transverse section of a modified form of curtain. Fig. 9 is a plan of such modified form of curtain assembly. Fig. 10 a side elevation thereof, Fig. 11 an end elevation of one member of the curtain assembly, and Fig. 12 a transverse section of a still further modified form of curtain member and assembly. My improved form of curtain comprises an assembly of separate removable refractory members having, in general, a plate-like form, one distinguishing feature being, the method of maintaining opposing members of the assembly in position by means of a strut-like projection or separate member between same.

Referring to Figs. 1, 2, and 3, showing a type of cell to which my improved curtain is adapted, 1 is a cathode cell pot set in a furnace adapted to supply initial or control heat for the bath. A. single anode or apluralit 2 depend in the bathfrom above and are pre erably set in a straight line between opposing .cathode surfaces of the pot. The anodes are further preferably supported by adjustable hangers permitting motion in a vertical direction, removal of anodes from the bath, reinsertion therein and for adjusting the depth ofdipping in the bath.

In the type of cell illustrated, the pot is provided with an inverted trough 3, adapted to tra liberated metal rising through the bath rom the principal cathode surface 4 of the pot. Such metal is shown at 5 in the cross hatched areas. The bath level will be approximately as shown in Figs. 1 and 2. Provision may be advisedly made to lead the light metal so entrapped to a collecting well or gathering zone permitting easy access for removing the so-collected metal. Such a collecting well is shown at 12 and the metal collected therein at 13. A second well 14, shown beside 12 in the plan view Fig. 3, is separated from the well 12 by the partition 15 and affords access to the cell for the insertion of a dipper or like utensil by means of which sediment or so called sludge may be dredged from the bath while the cell is in operation. The metal collecting in the well 12 may likewise be dipped or otherwise removed from the cell without interrupting operations. One side 6 of the inverted trough adjacent the collecting well 12 is removed to enable the metal entrapped therein to float out into the collecting well. The removed side is shown in dotted lines as 6 in Fig. 2. which dotted lines also may be taken to represent the unremoved portion thereof adjacent the well 14.

The curtain separating the anodic from the cathodic bath areas is preferably composed of an assembly of refractory plate-like members having surface projections or other equivalent contours enabling the support thereof upon the cell superstructure. Such a curtain is illustrated in longitudinal cross section in Fig. 2 in plan in Fig. 3, and in transverse section in 1. As seen in the plan Fig. 3 the curtain is composed of two U-shaped end members 7 and two H-shaped intermediate members 8. All such members are provided with a projecting flange resting upon a ledge of the cell superstructure 9. If more or less than three anodes are employed there will be a corresponding increase or decrease in the number of intermediate curtain members 8. The curtain illustrated in Figs. 1, 2, and 3, is shown separately in Figs. 4, 5, and 6. Fig. 4 isa cross section on the line AB of Fig. 5 and the partial cross sectlon in Fig.

6 is on the line CD of Fig. 5. The U-shaped member 7 in Fig. 5 is of the same outline as shown in Fig. 3 but a variation thereof is shown at ,7 in which two L-shaped memhere, right and left end, are employed 1n assembly as the equivalent of the U-shaped members 7, such construction being an alternative one. Projections 10 may be rovided with holes in which will permit the insertion of a tool or other hook shaped device for lifting or otherwise handling the members in the operations hereafter described. The 1nd1v1dual curtain members 8 will be seen to be composed of two plate-like portions separated by a strut integral therewith. The strut is shown at 11. The members 8, as well as 7 are carried on their projecting flange by a ledge in the superstructure of the cell and form together a rectangular inclosure about the anodes separating same from the cathode. The curtain members also blanket the exposed surfaces of the inverted trough 3 restricting cathodic action thereon to a minimum which is highly desirable since metal liberated thereon would not normally enter the trap be advisedly provided for the collecting well 12 and the dredging well 14.

A further alternative form of curtain member and assembly is shown in Figs. 8, 9, 10 and 11 in which the end members 7 are similar to those heretofore described, while the intermediate members 8 and 8' are T shaped and plate shaped respectively. The stem of the T of one acting as a strut, bearing against the plate form member opposed to the T form member. The construction is readily understood, particularly by referring to the edge view of the member 8 shown in full lines in Fig. 11 and of the member 8' shown in dotted lines therein. A still fur ther modification of an intermediate curtain member such as 8 and 8 is shown in Fig. 12 where two similar plate-like members 8' are separated by a separate strut-like member 8 resting upon same as indicated in the drawing. The oflice of the struts shown in the various Figs. 'is to maintain the opposing members of the curtain assembly in their proper position and space relation.

It will be obvious that other forms of sup port for the curtain members may be employed, such as pegs or thelike, from which the curtain members may be hung,.without departing from the spirit of my invention so long as the opposed members of the curtain are separated by strut-like integral or separate members therebetween.

Various other forms of plates and struts may also be employed without departing from the spirit of my invention but suflicient variety has been shown to indicate to one skilled in the art further variations thereof.

When in the course of operation of an electrolytic cell employing curtain members of the type herein disclosed in an assembly such as shown or an equivalent thereof, should one or more members of the assembly become eroded or otherwise unfit for further service it may be replaced with a new member without interrupting the operation of the cell. To do this I provide in a convenient location such new member with its integral strut or without same depending upon the precised detailed, forms employed heated approximately to the temperature of the bath. I then remove one or more of the cover plates 17 giving access to the member to be replaced.

I then insert a tool fitted to engage with the member and/or strut to be removed, lift it out of the assembly and then with a similar tool or equivalent replace same with the preheated new member previously referred to. The separate strut if employed would then be replaced or a new one inserted if required.

The covers may then be replaced and operation again become normal. During the time that the covers are removed sufiicient suction will be desirably maintained upon the outlet 19 to avoid the issue of anodic gas into the room. During the operations just described the cell may be continued in operation without loss of output.

My invention is applicable toadvantageous use in both large and small scale operation. It is particularly applicable in large scale operations employing a plurality of anodes in a large cell. A sectional curtain for such a cell may be readily constructed of small pieces or plates of the character described to form a rectangular, oval, circular, or other enclosure or partition for leading the anodic gas to the outlet, for covering exposed portions of the pot upon which it is desired to restrict'cathodic action, and for separating the floating metal from the anodic products. Such a curtain may be constructed far more cheaply and safely than a large sized single 1 piece curtain and renewals will be confined to the replacement of small pieces for any one breakage whereas when large single piece curtains are used, breakage at a single point will require the substitution of a new piece of large size and cost. Not only are small refractory pieces more cheaply made than large ones but they sufi'er less breakage in drying, burning, packing, shipping, and storage. They require less boxing and packing materials for shipment, less storage room and less labor in handling, are in many respects highly advantageous relative to large sized pieces. I have found the disadvantage incident to the discontinuous character of the curtain. due to the more or less imperfect joint obtainable in actual practice between the adjoining plate edges, to present no serious difiiculties in operation. It is customary to employ a suction upon the anodic gas chamber of the cell which effectually prevents issue of the chlorine through the joints in the curtain, and such joints are suficiently close in practice to substantially prevent metal from passing into the anodic compartment from without. In the form of cell construction illustrated in Fi 1, the bulk of the metal liberated is trapped as indicated, and but a small portion is liberated upon the surfaces of the metal adjacent to the curtain to become later liable to passage in part through the curtain joints into the anodic gas chamber before removal as metal product.

I have described my invention employing refractory material for the curtain. plates.

Among materials available are ceramic ma- .terials, sintered or fused magnesia, alumina part of one or more portions or members of' the curtain assembly or that it may be a separate and distinct piece adapted to engage with the members to be held in place by it, and I further conceive my invention to cover all equivalent varieties of forms or shapes of the curtain members or the transverse strut employed therewith.

Other modes of applying the principle of my invention may be employed instead of the one explained, change being made as regards the mechanism herein disclosed, provided the means stated by any of the following claims or the equivalent of such stated means be employed.

I therefore particularly point out and distinctly claim as my invent1on:--

1. In apparatus for electrolyzing a fused salt bath, a closed sectional partition of refractory material to separate anode and cathode products comprising a plurality of generally plate-shaped members provided 5 with means to suspend the same vertically from a support, and strut members disposed transversely between oppositely placed plate members.

2. In apparatus for electrolyzing a fused .salt bath, a closed sectional partition of refractory material to separate anode and cathode products comprising a plurality of generally plate-shaped members provided with means to suspend thesame vertically from a support, and strut members joining oppositely placed pairs of plate members, such strut members being formed integrally with at least one of each pair of plate members.

3. In apparatus for electrolyzing a fused salt bath, a closed sectional partition of refractory material to separate anode andcathode products comprising end members provided with a flange on the outer face to sus end the same vertically from a support an having at least two sides, such sides being dis osed approximately at right angles to eac other, similarly flanged plate-like intermediate members and strut members joining oppositely placed intermediate members.

4. In apparatus for electrolyzing a fused.

salt bath, a closed sectional partition of refractory material to separate anode and cathode products comprising end members provided with a flange on the outer face to suspend the same vertically from a support and having at least two sides, such sides being disposed approximately at right angles to 5 each other, similarly flanged plate-like inter mediate members and strut members joining and formed integrally with at least one of each pair of oppositely placed intermediatemembers. 1O 5. In apparatus for electrolyzing a fused salt bath, a closed sectional partition of refractory material to separate anode and cathode products comprising U-shaped end members provided with a flange on the outer face to suspend the same vertically from a support, similarly flanged plate-like intermediate members and strut members joining oppositely placed intermediate members.

6. In apparatus for electrolyzing a fused salt bath,a closed sectional partition of refractory material to separate anode and cathode products comprising U-shaped end members provided with a flange on the outer face to suspend the same vertically from a support, similarly flanged plate-like intermediate members and strut members joining and formed integrallywith at least one of each pair of oppositely placed intermediate memers. so 7. In apparatus for electrolyzing a fused salt bath, a closed sectional partition of refractory material to separate anode and cathode products comprising two U-shaped end members provided with a flange on the outer face to suspend the same vertically from a support, and a plurality of H-shaped intermediate members consisting of two opposed similarly flanged plate-like sections oined by a strut section. Signed by me this 26 day of July, 1929.

LOUIS E. WARD. 

